| Zebibits per second (Zibit/s) | Megabits per second (Mbit/s) |
|---|---|
| 1 Zebibit per second | 1.18059162072 × 1015 Mbit/s |
| 2 Zebibits per second | 2.36118324143 × 1015 Mbit/s |
| 3 Zebibits per second | 3.54177486215 × 1015 Mbit/s |
| 4 Zebibits per second | 4.72236648287 × 1015 Mbit/s |
| 5 Zebibits per second | 5.90295810359 × 1015 Mbit/s |
| 10 Zebibits per second | 1.18059162072 × 1016 Mbit/s |
| 20 Zebibits per second | 2.36118324143 × 1016 Mbit/s |
| 25 Zebibits per second | 2.95147905179 × 1016 Mbit/s |
| 50 Zebibits per second | 5.90295810359 × 1016 Mbit/s |
| 100 Zebibits per second | 1.18059162072 × 1017 Mbit/s |
| Reference | Zebibits per second (Zibit/s) | Megabits per second (Mbit/s) |
|---|---|---|
| A dial-up modem | 4.74338 × 10-17 Zibit/s | 0.056 Mbit/s |
| Typical home broadband | 8.47033 × 10-14 Zibit/s | 100 Mbit/s |
| Gigabit Ethernet | 8.47033 × 10-13 Zibit/s | 1000 Mbit/s |
| Streaming a 4K film | 2.11758 × 10-14 Zibit/s | 25 Mbit/s |
The zebibit per second is a unit of data transfer rate equal to two to the seventieth power bits per second, which is 1,024 exbibits per second. Its symbol is Zibit/s. It is the binary counterpart of the zettabit per second, and the two differ by 18.1 per cent — approaching a fifth.
Nothing runs at this rate, and nothing is designed to. A zebibit per second is about a thousand times the total instantaneous traffic of the internet, and it would move the world's entire stock of stored data in a matter of minutes. The unit exists because the IEC series, like the metric series it parallels, was defined completely rather than only as far as anyone then needed.
That completeness is a deliberate design principle rather than an oversight. A measurement system whose names run out at some arbitrary point forces every future user to improvise an extension, and improvised extensions conflict with one another. Defining the whole ladder in advance costs nothing and removes the possibility.
The eighteen per cent gap at this level is the clearest illustration of why the binary series was needed at all. At the kibibit the two conventions differed by 2.4 per cent, which nobody noticed; the discrepancy multiplies by 1.024 at each step, and by here it is large enough that no reader could treat the two labels as interchangeable even in casual writing.
In octets a zebibit per second is 147,573,952,589,676,412,928, or 128 exbioctets per second. Expressing the same rate in every unit on the scale is an exercise rather than an application, but it is one a converter has to perform correctly, because the arithmetic does not become approximate when the quantity becomes unreachable.
The practical lesson is the one the whole binary series teaches: the lowercase i is not optional. It is the only mark in a written figure that distinguishes a power of two from a power of ten, and by this point in the scale the two are nearly a fifth apart.
One zebibit per second equals 1,024 exbibits per second, 147,573,952,589,676,412,928 octets per second, or about 1.181 zettabits per second.
The megabit per second is a unit of data transfer rate equal to one million bits per second. Its symbol is Mbit/s, often written Mbps. It is the unit in which internet connections are sold, which makes it the data unit most people encounter by name.
Because it is a decimal million and not 1,048,576, the conversion to octets is exact and easy: one megabit per second is 125 kilooctets per second, so a hundred-megabit connection delivers about 12.5 megaoctets per second at best. Anyone who watches a file transfer and does the division has understood the entire relationship between how connections are advertised and how transfers are reported.
What a household actually needs is far below what it usually buys. Standard-definition video streaming uses about 3 megabits per second, high definition about 5, and ultra-high definition about 25. A video call is around 3 to 8. A large family watching four separate high-definition streams while somebody downloads a game is using perhaps 60 megabits per second, which a hundred-megabit connection handles comfortably.
The reason to buy more capacity than that is not peak speed but behaviour under load. A link that is near its limit develops queues, and queues add delay, which shows up as stutter in video calls and lag in games. A connection with generous headroom keeps its latency low, and that is a more noticeable improvement than a higher number on a speed test.
Wired local networks pass through this range on the way up. The original Ethernet ran at 10 megabits per second, its successor at 100, and both were the standard office connection for a decade each before gigabit replaced them. Wireless standards followed the same path with a lag, and both are now measured in hundreds of megabits or in gigabits.
Real throughput is always below the nominal rate. Protocol overhead takes 5 to 10 per cent on a wired link; a shared wireless channel loses much more, because the medium is divided between all the devices using it and interference forces retransmission. A connection advertised at 100 megabits per second measured at 90 over cable and 50 over a busy wireless network is behaving normally.
One megabit per second equals 1,000,000 bits per second, 125 kilooctets per second, or about 0.9537 mebibits per second.